Electrophysiological responses of gustatory sensilla of Mamestra brassicae(Lepidoptera, Noctuidae) larvae to three ecdysteroids: ecdysone, 20-hydroxyecdysone and ponasterone A

Specialised phytophagous Lepidoptera such as Bombyx mori and Pieris brassic ae have contact chemoreceptors that perceive ecdysteroids at very low conce ntrations. This sensory perception allows them to feed on substrates with a high content of phytoecdysteroids. We have evaluated if a polyphagous inse ct like Mamestra brassicae does possess contact chemoreceptor cells that ar e sensitive to these molecules. Electrophysiological recordings were perfor med from contact chemoreceptors located on the maxilla. These receptors wer e stimulated with some sugars, amino acids and salts and with three ecdyste roids. Our results demonstrate that a specific cell within the lateral sens illa responds to 20-hydroxyecdysone and ponasterone A but not to ecdysone. (C) 1999 Elsevier Science Ltd. All rights reserved.